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Unformatted text preview: Gestation Length Cow 282 days Sow 3 weeks 114 days Mare 336 days Ewe 2-2 1/2 150 days Bird Every day 1 day Fertilization Usually occurs 24-36 hours after copulation in mammals and birds within 15-20 minutes of ovulation Chicks develop completely in the egg and are independent of maternal care Placenta Provide nutrients and vital gases Removal of waste products Production of hormones to maintain pregnancy Chicks develop a placenta-like structure that provides an avenue for nutrients Parturition Defined as giving birth Around time of birth the hormone prolactin increases to stimulate milk synthesis Hormone oxytocin brings about steady contractions Breeding Artificial Insemination More genetic improvement through the use of sires...
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- Winter '09